Provent Part 2
12-06-2013, 05:37 PM
#18
Three Wheelin'
Ducman,
Maybe I missed it but is this one of DR's systems that you added the pump to?
Did you try using the Provent without the pump?
I'm asking because I was speaking with the group last weekend about oil control as I'm getting more puddling in intake that I'd like and was thinking that since DR's not selling the Provent system anymore a home-made one may be in order. TIA.
Maybe I missed it but is this one of DR's systems that you added the pump to?
Did you try using the Provent without the pump?
I'm asking because I was speaking with the group last weekend about oil control as I'm getting more puddling in intake that I'd like and was thinking that since DR's not selling the Provent system anymore a home-made one may be in order. TIA.
12-06-2013, 06:37 PM
#20
Supercharged
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yep... I missed that. D'oh!You are venting oil and [at times excess] air out of the crankcase through the aid of a vacuum pump.
This oil/air mixture is then separated, with the "clean" air exiting the Provent. The oil is left to return via the drain. The oil and some new air is pulled back into the system via the head because of the negative pressure introduced by the addition of the vacuum pump.
So, in the best case scenario, when there is no blowby, the CFM cleared by the vacuum pump will be directly re-introduced via the crankcase. This should not pose any issues that I can think of off hand.
When there is blowby, as long as the CFM does not exceed the capacity of the vacuum pump, you should still have negative crankcase pressure. The oil should be a net sum (i.e. the oil that comes out goes right back in). Any excess air should come out the Provent.
I assume you have some type of check valve on the oil drain?
12-06-2013, 06:43 PM
#21
Electron Wrangler
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On a GTS you need more than the DR configured Provent - tried that - earlier models not so sure how big an issue it is...
I too have a vacuum pump (inplace of the airpump) - same pump as in Colin's/Jake's set-up.
Provides some new plumbing challenges and lots of new configuration issues to consider/solve. For me using up 1 quart of oil every 500 miles or so (sometimes less) was very excessive and was leading to many other issues I'd rather avoid.
The oil control on a 928 is a real problem - Porsche made it worse over time and the GTS is likely the worst of all... It would seem Porsche either didn't really know what to do about it OR didn't want to bother to do enough.
It did certainly get worse with age (the car's) - but for me it was never ever good.
...Mine is more of a continually modifed Alan set-up
Alan
I too have a vacuum pump (inplace of the airpump) - same pump as in Colin's/Jake's set-up.
Provides some new plumbing challenges and lots of new configuration issues to consider/solve. For me using up 1 quart of oil every 500 miles or so (sometimes less) was very excessive and was leading to many other issues I'd rather avoid.
The oil control on a 928 is a real problem - Porsche made it worse over time and the GTS is likely the worst of all... It would seem Porsche either didn't really know what to do about it OR didn't want to bother to do enough.
It did certainly get worse with age (the car's) - but for me it was never ever good.
...Mine is more of a continually modifed Alan set-up
Alan
Last edited by Alan; 12-06-2013 at 07:22 PM.
12-06-2013, 06:48 PM
#22
Thread Starter
no check valve needed. i never see positive pressure. i get "low vacuum" at idle, prob around 2hg. then when running at temp around 10-12HG. i have yet to have any oil or anything come out that filter on the provent (the KNN filter). it lets fresh air in, or vapors out if i had some CFM surge etc.
no need for a check valve. oil can't flow backwards in the line. i have cleaned the provent housing than checked it after some spirited driving. only the slightest showing of oil film. mist would be to much. :-P
been working fantastically, just decided to move it.
no need for a check valve. oil can't flow backwards in the line. i have cleaned the provent housing than checked it after some spirited driving. only the slightest showing of oil film. mist would be to much. :-P
been working fantastically, just decided to move it.
12-06-2013, 07:03 PM
#23
Electron Wrangler
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There is always some blowby at any rpm/load - even without fuel/spark/combustion (e.g. on the overrun) - because there is always at least some air compression loss past the rings. So while the flow is very variable - there is always a net flow out the provent filter/output. So all 'recirculated' fluid is in fact truly just recirculated.
Some fresh air flushing may actually be desirable (the stock systems gets you some) - but excess flow through the provent at high rpm/high blowby certainly is not - so its a challenge to manage flushing for only low flow cases.
Alan
12-06-2013, 07:09 PM
#25
Nordschleife Master
Ah what the hell, I'll give a little more information.
The stock crankcase system design for all 32V cars was fatally flawed right out the door.
All of the "kits" that had/have/are produced by others are merely small modifications to this flawed system.
I looked at this from a clean slate point of view and with the intent of eliminating pretty much all of the factory points of failure.
There are a number of reasons that the GTS has more issues than the S4. But the main two reasons are, the pistons did not receive the holes in the oil control rings which aid in the return of the oil into the sump. The second is the increased stroke of the GTS motor increased the pressure surges in the crankcase enough to cause ring flutter.
With the newer engines (coyote), they are doing interesting things to balance the pressure pulses from pairs of cylinders. This is simply not feasible on our engines without a completely redesigned engine block. The one way to eliminate these pressure pulses which are formed naturally is to reduce the crankcase from being atmospheric (or higher) pressure, to being less than atmospheric pressure.
As Alan has said, he had extreme oil consumption prior to this system being installed. Since the install his oil consumption has dropped right off.
I just installed this system on a 93 GTS that was going through 1L of oil every 500km. Prior to this he had installed a system from one of our big vendors which was supposed to drastically reduce the problem. His consumption remained the same. Since the install of this kit, his engine has consumed no real amount of oil. It has leaked a little as we had a fitting loosen a little, and his oil pan gasket has failed, but there has been no sign of any oil consumption what so ever. He would get a blue smoke on acceleration, and especially on deceleration (engine braking down a hill), now there is no smoke no matter how hard he drives it.
I am just making the last few parts for this and then Roger will make a post with all the fine details etc.
The stock crankcase system design for all 32V cars was fatally flawed right out the door.
All of the "kits" that had/have/are produced by others are merely small modifications to this flawed system.
I looked at this from a clean slate point of view and with the intent of eliminating pretty much all of the factory points of failure.
There are a number of reasons that the GTS has more issues than the S4. But the main two reasons are, the pistons did not receive the holes in the oil control rings which aid in the return of the oil into the sump. The second is the increased stroke of the GTS motor increased the pressure surges in the crankcase enough to cause ring flutter.
With the newer engines (coyote), they are doing interesting things to balance the pressure pulses from pairs of cylinders. This is simply not feasible on our engines without a completely redesigned engine block. The one way to eliminate these pressure pulses which are formed naturally is to reduce the crankcase from being atmospheric (or higher) pressure, to being less than atmospheric pressure.
As Alan has said, he had extreme oil consumption prior to this system being installed. Since the install his oil consumption has dropped right off.
I just installed this system on a 93 GTS that was going through 1L of oil every 500km. Prior to this he had installed a system from one of our big vendors which was supposed to drastically reduce the problem. His consumption remained the same. Since the install of this kit, his engine has consumed no real amount of oil. It has leaked a little as we had a fitting loosen a little, and his oil pan gasket has failed, but there has been no sign of any oil consumption what so ever. He would get a blue smoke on acceleration, and especially on deceleration (engine braking down a hill), now there is no smoke no matter how hard he drives it.
I am just making the last few parts for this and then Roger will make a post with all the fine details etc.
12-06-2013, 07:11 PM
#26
Nordschleife Master
12-06-2013, 08:11 PM
#28
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Colin's vacuum system is going on my GTS as the "Provent" system was more of a band aid than a fix.
This is a MUST for GTS owners.
More power with zero/less carbon buildup
This is a MUST for GTS owners.
More power with zero/less carbon buildup
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
